A turbo chiller is a large-capacity heat source device which is widely used in applications such as air conditioning of a large-scaled factory having a clean room, such as an electrical and electronic related factory, or district heating and cooling. As the turbo chiller, a turbo chiller unitized by disposing configuration devices such as a compressor, a condenser, and a vaporizer near each other and integrating the configuration devices is known (refer to, for example, PTL 1).
As the turbo chiller, a type in which a two-stage centrifugal compressor is used as a compressor and an intercooler is joined to the downstream of a first compression stage is known. Specifically, a gas refrigerant cooled in the intercooler is introduced to the downstream of the first compression stage through an intermediate suction chamber which surrounds an inlet portion of a second impeller configuring a second compression stage, and a slit formed between the intermediate suction chamber and a suction flow path provided around the inlet portion of the second impeller.
Further, in the turbo chiller having such a centrifugal compressor, in order to control an operating range of the chiller, movable vanes in which an angle is changed according to the operation conditions are respectively provided in impellers configuring the first compression stage and the second compression stage. The movable vane is driven by a driving device integrally provided in the centrifugal compressor. However, a portion (referred to as a drive mechanism) of the driving device is installed in the intermediate suction chamber.
Usually, the drive mechanism which is installed in the intermediate suction chamber is installed at the position of 180° in a circumferential direction from a suction nozzle for introducing a gas refrigerant into the intermediate suction chamber, that is, the farthest position with respect to the suction nozzle, in order to reduce the distribution in a circumferential direction of a flow at the joining position between an outlet of the intermediate suction chamber and a main flow path.
Further, PTL 2 discloses a centrifugal compressor having a shape which leads a large quantity of fluid to one side in a circumferential direction in order to make the centrifugal compressor compact, in a suction flow path for introducing the fluid into an impeller of the centrifugal compressor.